Colonic Drug Delivery System Research Articles

Colonic drug delivery systems: Exploring the potential of biodegradable polymers for systemic effects

Targeted drug delivery to the colon is highly desirable for the local treatment of various bowel diseases, including ulcerative colitis, Crohn’s disease, amebiasis, and colonic cancer, as well as for the systemic delivery of protein and peptide drugs. The colon-specific drug delivery system (CDDS) must protect the drug during transit through the stomach and small intestine, ensuring that release and absorption occur only in the colon. The colon is an ideal site for drug absorption due to its lower enzymatic activity compared to the small intestine, which helps protect peptide drugs from degradation, and its long residence time, which enhances systemic bioavailability.While the oral route is the most convenient for CDDS, rectal administration is also used, though it can be uncomfortable and less effective for targeting the proximal colon. Intrarectal drug preparations, such as solutions, foams, and suppositories, are used for both systemic dosing and local treatment of the large intestine. The efficacy of these drugs often depends on their formulation, spreading capacity, and retention time.The colon’s high water absorption capacity and viscous contents can limit drug availability to the absorptive membrane. However, the presence of a diverse bacterial flora in the colon can be leveraged for drug metabolism and targeted delivery of peptide-based macromolecules, such as insulin. Understanding the anatomy and physiology of the gastrointestinal tract (GIT), including variations in pH, is crucial for designing effective CDDS. This knowledge helps optimize drug release and absorption, ultimately improving therapeutic outcomes for patients.

Advances in colon-targeted drug technologies.

Herein, we present an overview of innovative oral technologies utilized in colonic drug delivery systems that have made significant translational and clinical advancements to treat inflammatory bowel disease (IBD) in recent years. The colon is home to distinct physiological conditions, such as pH and microbiota, that have been exploited in the development of colonic drug delivery systems for the treatment of local and systemic diseases. However, given the intra and interindividual variability in the gastrointestinal tract of both healthy and diseased states, various systems have shown inconsistencies in targeted drug release to the colon. Recent breakthroughs have led to systems that incorporate multiple independent trigger mechanisms, ensuring drug release even if one mechanism fails due to physiological variability. Such advanced platforms have bolstered the development of oral biologics delivery, an especially promising direction given the lack of commercially available oral antibody medications for IBD. These concepts can be further enhanced by employing 3D printing which enables the personalisation of medicines. Leveraging these novel technologies can accurately deliver therapeutics to the colon, allowing for treatments beyond gastrointestinal tract diseases. To realize the full potential of colonic drug delivery, it is paramount that research focuses on the clinical translatability and scalability of novel concepts.

Development of intestinal colonic drug delivery systems for diverticular disease: A QbD approach

This study aimed to advance the development of intestinal colon-coated sustained-release matrix tablets of metronidazole for diverticulitis treatment, employing the Quality by Design (QbD) methodology. Comprehensive Risk analysis and Risk evaluation were conducted to assess the potential risks associated with Critical Material Attributes (CMA) and Critical Process Parameters (CPP). Ishikawa diagram, color-coded risk classification and the Risk Priority Number (RPN) were used as tools for risk evaluation. A Design of Experiments (DoE) was executed using a fractional factorial design, incorporating five key factors derived from the Risk analysis and Risk evaluation. Two levels and a central point were established for each factor, resulting in 28 batches of coated tablets. The manufacturing process involved direct compression, followed by a coating process using pH-dependent or time-dependent polymers. Characterization and dissolution studies were conducted on all batches, and the obtained results underwent analysis of variance (ANOVA).The findings demonstrated the robustness and reproducibility of both the direct compression and coating processes. Statistical analysis identified HPMC/chitosan ratio, blending time, coating polymer, and coating weight gain as factors significantly impacting drug release. A Design Space was established to delineate the interplay of these factors, offering insights into various combinations influencing drug release behavior. Thus, the design space for 10 % weight gain formulations includes a range of HPMC/CH ratios between 2.7–3 and mixing times between 10 and 12 min; for 20 % weight gain formulations it includes a range of HPMC/CH ratios up to 2 and mixing times between 10 and 16 min. Multiple Linear Regression between technological and biopharmaceutical variables were optimized facilitating scale-up operations. Batches with a 10 % weight increase and varied HPMC viscosity grades and coating polymers achieve ∼50 % drug release at 24 h; however, batches with a 20 % weight increase along, with either high proportions of HPMC and short blending times or low proportions of HPMC and longer blending times, achieve slow release of metronidazole. This study contributes to optimizing metronidazole colonic delivery systems, enhancing their potential efficacy in diverticulitis treatment.

Pectin-Chitosan Hydrogel Beads for Delivery of Functional Food Ingredients.

A common challenge in hydrogel-based delivery systems is the premature release of low molecular weight encapsulates through diffusion or swelling and reduced cell viability caused by the low pH in gastric conditions. A second biopolymer, such as chitosan, can be incorporated to overcome this. Chitosan is usually associated with colonic drug delivery systems. We intended to formulate chitosan-coated pectin beads for use in delaying premature release of the encapsulate under gastric conditions but allowing release through disintegration under intestinal conditions. The latter is of utmost importance in delivering most functional food ingredients. Therefore, this study investigated the impact of formulation and process conditions on the size, sphericity, and dissolution behavior of chitosan-coated hydrogel beads prepared by interfacial coacervation. The size and sphericity of the beads depend on the formulation and range from approximately 3 to 5 mm and 0.82 to 0.95, respectively. Process conditions during electro-dripping may be modulated to tailor bead size. Depending on the voltage, bead size ranged from 1.5 to 4 mm. Confocal laser scanning microscopy and scanning electron microscopy confirmed chitosan shell formation around the pectin bead. Chitosan-coated beads maintained their size and shape in simulated gastric fluid but experienced structural damage in simulated intestinal fluid. Therefore, they represent a novel delivery system for functional food ingredients.

Methacrylic Acid Co-Polymers: Crucial agents for the Colon Targeted Oral Drug Delivery System

The objective of this research was to formulate an Ornidazole tablet capable of delivering the drug intact to the colon for the treatment of IBD, ulcerative colitis, and Crohn's disease. In the current investigation, pH-independent and pH-dependent polymers were used to target the Ornidazole tablet to the colon. This study evaluated two time-dependent (sustained release) polymers (Eudragit RS and Eudragit RL) and one pH-dependent polymer (Eudragit S100). The influence of the two formulation variables of the colon drug delivery system on the two response variables were examined simultaneously using a statistical 32-Full factorial design. X1 Ratio of Eudragit RS 100 to Eudragit RL 100 and X2 % weight gain with Eudragit S 100 were treated as independent variables in a factorial design, while Y5 and Y12 were treated as dependent variables. Through this procedure, a total of nine F9 samples were produced. Y5 in-vitro release should not exceed 10%, whereas Y12 should surpass 85%. Based on these results, batch B8 is considered the finest of all cohorts. According to the results, the enhanced formulation provides optimal intact drug delivery to the targeted region.

Colon Drug Delivery Systems Based on Swellable and Microbially Degradable High-Methoxyl Pectin: Coating Process and In Vitro Performance.

Oral colon delivery systems based on a dual targeting strategy, harnessing time- and microbiota-dependent release mechanisms, were designed in the form of a drug-containing core, a swellable/biodegradable polysaccharide inner layer and a gastroresistant outer film. High-methoxyl pectin was employed as the functional coating polymer and was applied by spray-coating or powder-layering. Stratification of pectin powder required the use of low-viscosity hydroxypropyl methylcellulose in water solution as the binder. These coatings exhibited rough surfaces and higher thicknesses than the spray-coated ones. Using a finer powder fraction improved the process outcome, coating quality and inherent barrier properties in aqueous fluids. Pulsatile release profiles and reproducible lag phases of the pursued duration were obtained from systems manufactured by both techniques. This performance was confirmed by double-coated systems, provided with a Kollicoat® MAE outer film that yielded resistance in the acidic stage of the test. Moreover, HM pectin-based coatings manufactured by powder-layering, tested in the presence of bacteria from a Crohn's disease patient, showed earlier release, supporting the role of microbial degradation as a triggering mechanism at the target site. The overall results highlighted viable coating options and in vitro release characteristics, sparking new interest in naturally occurring pectin as a coating agent for oral colon delivery.

Colon-targeted 3D-Printed mesalamine tablets: Core-shell design and in vitro/ex-vivo evaluation

ObjectivesThe present study is intended to develop a shell-core tablet using a hot melt extrusion (HME)-based dual-nozzle fused deposition modeling (FDM) three-dimensional (3D) printing approach. The primary objective was to establish a sustained-release colonic drug delivery system and improve mesalamine's permeability by incorporating Vitamin E TPGS as a permeation enhancer. MethodThe study utilized Kollidon® SR for sustained release, L-100, and HPMC HME L100 for the tablet's protective shell. Six filament formulations were tested, and the mechanical properties of the shell filaments, including the three-point bending, Hooke's law, and stiffness, were assessed. Drug release profiles of the tablets were evaluated using the USP-II dissolution apparatus, and permeability characteristics were gauged using the non-everted intestinal sac method. Solutions containing 5% w/v mesalamine and 2.5% w/v Vitamin E TPGS were employed, with pure mesalamine as a control. ResultsOptimal filament ratios were identified as 50:50 for the core and 30:70 for Eudragit L-100 to HPMC HME L100 for the shell. The resulting tablets achieved a prolonged drug release of up to 24 h for the core. They ensured minimal drug release in the upper gastrointestinal tract (∼5% in the first 5 h), effectively targeting the colon. Incorporating Vitamin E TPGS led to a 3.6-fold increase in mesalamine absorption compared to the control, and the addition of Kollidon® SR notably improved the flow properties of Mesalamine powder. ConclusionIn conclusion, this innovative approach has the potential to achieve a colon-specific drug delivery system.

MUKOADEZİF POLİMERLERİN KOLON HEDEFLİ İLAÇ TAŞIYICI SİSTEMLERDE KULLANIMI: DETAYLI BİR İNCELEME

Objective: Mucoadhesive polymers have emerged as crucial components in the realm of drug delivery systems, particularly in the context of targeted treatments within the colon. These polymers possess adhesive properties that enable them to form temporary bonds with mucosal surfaces, extending the contact time of drugs with the colonic mucosa. This review provides a comprehensive overview of mucoadhesive polymers for colon drug delivery systems. Natural polymers such as chitosan and alginate, along with synthetic counterparts like polyacrylic acid derivatives, find application in these systems. The advantages of mucoadhesive polymers lie in their ability to facilitate site-specific drug delivery, thereby minimizing systemic side effects, and in enabling controlled and sustained release of drugs for improved bioavailability. Despite these benefits, challenges including variability in mucosal conditions and the imperative need for biocompatibility must be addressed. The applications of mucoadhesive polymers span diverse medical conditions, including targeted delivery of anti-inflammatory drugs for inflammatory bowel diseases, localized administration of chemotherapeutic agents for colon cancer treatment, and precise delivery of antibiotics for colonic infections. Result and Discussion: As a promising avenue for optimizing colon drug delivery, mucoadhesive polymers offer great potential for the development of effective and well-tolerated treatments for various colonic disorders.

A REVIEW ON DEVELOPMENT OF COLON TARGETED DRUG DELIVERY SYSTEM

The purpose of this review was to select a promising drug delivery system for colon diseases. This review covers the development of Colon Targeted Drug Delivery System (CTDDS) using 36 y (1986-2022) data from various research and review articles. All fig. designed using by BioRender website. vThe colon-targeted drug delivery systems developed for the specific site drug delivery which applied for both local and systemic actions of the drug; since the drug targeted to be release within the colon, the unwanted systemic side effects are reduced along with it. Systemic side effects include organ damage, respiratory diseases and, cardiovascular damage and other illnesses. Colon-targeted drug delivery system used in the treatment of diseases in the colon, including ulcerative colitis, irritable bowel syndrome and colorectal cancer. The benefit of colon-targeted drug delivery besides the reduction of side effects also include protection from premature drug release or burst in the stomach or small intestine before reaching the colon. For the development of drugs with such benefits and advantages, drug delivery systems and approaches have used for Colon targeted drug delivery systems, varying from conventional colon-targeting drug delivery systems to novel approaches for Colon-targeted drug delivery systems. Conventional drug delivery includes the use of prodrugs, pH-dependent, time-dependent, matrix-based systems, polysaccharides-derived systems, and bio-adhesive system while novel approaches include types such as port system, pulsincap system, pressure-controlled system, osmotic controlled system, CODES, and the newest approach wish is the use of nanotechnology in colon targeted drug delivery. In this research both techniques reviewed, and their types discussed as well. The limitation of their uses and the advantage of each system discussed with a breakdown of the different mechanisms used to formulate such systems. A successful colon targeting delivery can release the drug to a specific segment in colon due to presence of different colonic enzymes formed by microorganisms that metabolize drug carrier linkage. Use of combined approaches i.e., conventional systems and newer approaches may be the best way to cure colon diseases using an optimized colon drug delivery system.

A review on fungal pullulan as a natural polymer focusing on targeted therapy for colon cancer and other pharmaceutical applications

AbstractColon cancer is the second most invasive cancer and fourth most common malignant neoplasm worldwide. Targeted oral colonic drug delivery systems have attracted considerable attention in the treatment of colon cancer due to their superior properties. However, the delivery of drugs safely and effectively to the target site of the colon tumor is a hindrance due to the complexity of the gastrointestinal structure. Herein, to achieve an effective delivery system specifically targeting the colon, we have taken concern by using natural polymer such as pullulan, signifying its flexibility and relevance in biomaterials science to design antineoplastic approaches. Here, we summarize the physicochemical properties, different pullulan derivatives and their biomedical application, several colon cancer‐related treatment, and pullulan and its derivatives‐based delivery systems towards colonic tissue.

PH-sensitive HPMCP-chitosan nanoparticles containing 5-aminosalicylic acid and berberine for oral colon delivery in a rat model of ulcerative colitis

Ulcerative colitis (UC) with continuous and extensive inflammation is limited to the colon mucosa and can lead to abdominal pain, diarrhea, and rectal bleeding. Conventional therapies are associated with several limitations, such as systemic side effects, drug degradation, inactivation, and limited drug uptake, leading to poor bioavailability. These restrictions necessitate drug delivery to the colon so that the drug passes through the stomach unchanged and has selective access to the colon. The present study aimed to formulate 5-aminosalicylic acid (5-ASA) and berberine (BBR) in chitosan nanoparticles cross-linked by HPMCP (hydroxypropyl methylcellulose phthalate) as a colon drug delivery system for UC. Spherical nanoparticles were prepared. They showed appropriate drug release in the simulated intestinal fluid (SIF), while the release did not occur in the simulated gastric fluid (SGF). They improved disease activity parameters (DAI) and ulcer index, increased the length of the colon, and decreased the wet weight of the colon. Furthermore, histopathological colon studies showed an improved therapeutic effect of 5-ASA/HPMCP/CSNPs and BBR/HPMCP/CSNPs. In conclusion, although 5-ASA/HPMCP/CSNPs showed the best effect in the treatment of UC, BBR/HPMCP/CSNPs, and 5-ASA/BBR/HPMCP/CSNPs were also effective in vivo study, and this study anticipated they could be helpful in future clinical applications for the management of UC.

Design, Development, and Optimisation of Smart Linker Chemistry for Targeted Colonic Delivery-In Vitro Evaluation.

Drug targeting is necessary to deliver drugs to a specific site of action at a rate dictated by therapeutic requirements. The pharmacological action of a drug can thereby be optimised while minimising adverse effects. Numerous colonic drug delivery systems have been developed to avoid such undesirable side effects; however, these systems lack site specificity, leaving room for further improvement. The objective of the present study was to explore the potential of amino-alkoxycarbonyloxymethyl (amino-AOCOM) ether prodrugs as a general approach for future colonic delivery. To circumvent inter- and intra-subject variabilities in enzyme activities, these prodrugs do not rely on enzymes but rather are activated via a pH-triggered intramolecular cyclisation−elimination reaction. As proof of concept, model compounds were synthesised and evaluated under various pH conditions, simulating various regions of the gastrointestinal tract (GIT). Probe 15 demonstrated excellent stability under simulated stomach- and duodenum-like conditions and protected 60% of the payload in a small intestine-like environment. Moreover, 15 displayed sustained release at colonic pH, delivering >90% of the payload over 38 h. Mesalamine (Msl) prodrugs 21 and 22 were also synthesised and showed better stability than probe 15 in the simulated upper GIT but relatively slower release at colonic pH (61−68% of Msl over 48 h). For both prodrugs, the extent of release was comparable to that of the commercial product Asacol. This study provides initial proof of concept regarding the use of a cyclisation-activated prodrug for colon delivery and suggests that release characteristics still vary on a case-by-case basis.

AN OVERVIEW: DEVELOPMENT OF COLON DRUG DELIVERY SYSTEM AND ITS APPLICATION AND LIMITATIONS

There are various routes of drug administration. Oral administration is considered the most preferred route in drug administration for systemic effects, but the oral administration is not suitable for people with ulcerative colitis, crohn's disease, bowel cancer, diarrhea, treatment of diseases that sensitive to circadian rhythms such as asthma and angina, as well as for steroids administration. The delivery of targeted drugs has the goal of achieving the desired therapeutic profile by delivering the drug to the target site. This study conducted by reviewing related articles based on specify keywords on Science Direct database that has been published for the last 10 y. In recent decades, research has been conducted to develop methods that can target drugs to specific organs. The focusing on targeted drug delivery system to the colon, the various ways that were carried out for its approach, as well as the evaluation. By this study, some challenges in the colon drug delivery system could be overcome along with new approaches.

Advancement in Therapeutic Intervention of Prebiotic-Based Nanoparticles for Colonic Diseases.

Intestinal flora has become a therapeutic target for the intervention of colonic diseases (CDs) with better understanding of the interplay between microbiota and CDs. Depending on unique properties and prominent ability of regulating the intestinal flora, prebiotics can not only achieve a colon-specific drug delivery but also maintain the intestinal homeostasis, thus playing a positive role in the intervention of CDs. Currently, different studies on prebiotic-based nanoparticles have been contrived for colonic drug delivery and have shown great potential in curing various CDs, such as colitis and colorectal cancer. Nevertheless, there is a lack of systematic survey on the use of prebiotic nanoparticles for the treatment of CDs. This review aims to generalize the state-of-the-art of prebiotic nanomedicines specific for CDs. The species and function of intestinal flora and various kinds of prebiotics available as well as their regulating effects on intestinal flora were expounded. A variety of prebiotic nanoparticles pertinent to colon-targeted drug delivery systems were illustrated with particular emphasis on their curative activities on CDs. The efficacy and safety of prebiotic-based colonic drug delivery systems (p-CDDs) were also analyzed. In conclusion, the synergy between prebiotic nanoparticles and their cargos may hold promise for the treatment and intervention of CDs.

Development of Polymeric-Based Formulation as Potential Smart Colonic Drug Delivery System.

Conventional oral formulations are mainly absorbed in the small intestine. This limits their use in the treatment of some diseases associated with the colon, where the drug has to act topically at the inflammation site. This paved the way for the development of a smart colonic drug delivery system, thereby improving the therapeutic efficacy, reducing the dosing frequency and potential side effects, as well as improving patient acceptance, especially in cases where enemas or other topical preparations may not be effective alone in treating the inflammation. In healthy individuals, it takes an oral medication delivery system about 5 to 6 h to reach the colon. A colonic drug delivery system should delay or prohibit the medication release during these five to six hours while permitting its release afterward. The main aim of this study was to develop a smart drug delivery system based on pH-sensitive polymeric formulations, synthesized by a free-radical bulk polymerization method, using different monomer and crosslinker concentrations. The formulations were loaded with 5-amino salicylic acid as a model drug and Capmul MCM C8 as a bioavailability enhancer. The glass transition temperature (Tg), tensile strength, Young’s modulus, and tensile elongation at break were all measured as a part of the dried films’ characterization. In vitro swelling and release studies were performed to assess the behavior of the produced formulations. The in vitro swelling and release evaluation demonstrated the potential ability of the developed system to retard the drug release at conditions mimicking the stomach and small intestine while triggering its release at conditions mimicking the colon, which indicates its promising applicability as a potential smart colonic drug delivery system.

PREPARATION AND EVALUATION OF CHITOSAN CAPSULE FOR COLON SPECIFIC DELIVERY OF CAPECITABINE

The prime objective of the present study was to develop enteric coated chitosan capsule containing capecitabine for targeting colorectal cancer cells. The study describes a new colonic drug delivery system utilizing capsule shells prepared from chitosan. Coating of drug filled chitosan capsule with pH dependent enteric polymer like HPMC K4M / Cellulose acetate phthalate provides it a special feature of releasing drug at colonic pH. The complex formation between HPMC K4M, cellulose acetate phthalate and chitosan capsule gives extended release of drug over longer period. The disintegration time of the developed enteric coated capsule (Batch F2) was found to be 78±0.86 min and drug release was observed to be 97 % at the end of 9 h in pH 8.5 buffer solution simulating the colon fluid. All the prepared batches exhibited no release of drug in the first 3 h in simulated gastric fluid pH 1.2 and intestinal fluid pH 6.8. Thus, the enteric coated chitosan capsule proved to be efficient to deliver the drug at colon in colorectal cancer disease, which minimizes the side effects, of anticancer drug in stomach and upper intestine.

A yolk-shell structured calcium phosphate modified with Eu for oral drug delivery

Ulcerative Colitis (UC) is a non-specific chronic inflammatory disease affecting the rectum and colon, and may cause irreversible damage to the structure and function of intestine. However, there are still many challenges in the treatment of UC. For instance, the enzyme-responsive oral colon drug delivery system (OCDDS) relying on the gut flora metabolites-azo reductase is commonly used in clinical treatment, but the susceptibility of the microbiota in the gut during onset limits its further application. Besides, time-dependent OCDDS is also vulnerable to different individual gastrointestinal functions and pathophysiological conditions, which results in early or late drug-release, thus limiting its bioavailability. Therefore, in this work, a pH responsive OCDDS was designed based on the pH change pattern of human digestive tract. Calcium phosphate carrier was synthesized by phosphorus source adenosine triphosphate (ATP) and calcium source calcium gluconate monohydrate (CG). Moreover, the pH responsive materials Eu (the mixture of Eudragit L100 and Eudragit S100) were successfully coated by emulsion solvent evaporation method. The final OCCDDS achieved pH-controlled drug delivery in simulate gastrointestinal environment. Good biocompatibility of OCCDDS has been demonstrated by MTT assay.

Developed meloxicam loaded microparticles for colon targeted delivery: Statistical optimization, physicochemical characterization, and in-vivo toxicity study.

The study aimed to fabricate and evaluate Meloxicam (MLX) loaded Hydroxypropyl Methylcellulose (HPMC) microparticles for colon targeting because MLX is a potent analgesic used in the treatment of pain and inflammation associated with colorectal cancer (CRC). Nevertheless, its efficiency is limited by poor solubility and gastrointestinal tracts (GIT) associated side effects. Seventeen formulations of MLX loaded HPMC microparticles were fabricated by the oil-in-oil (O/O)/ emulsion solvent evaporation (ESE) technique. A 3-factor, 3-level Box Behnken (BBD) statistical design was used to estimate the combined effects of the independent variables on the dependent variables (responses), such as the percent yield (R1), the entrapment efficiency (EE) (R2), mean particle size (R3) and in vitro percentage of cumulative drug release (R4). For physicochemical characterization FTIR, XRD, DSC, and SEM analyses were performed. Biocompatibility and non-toxicity were confirmed by in-vivo acute oral toxicity determination. The percentage yield and EE were 65.75-90.71%, and 70.62-88.37%, respectively. However, the mean particle size was 62.89-284.55 μm, and the in vitro cumulative drug release percentage was 74.25-92.64% for 24 hours. FTIR analysis showed that the composition of the particles was completely compatible, while XRD analysis confirmed the crystalline nature of the pure drug and its transition into an amorphous state after formulation. DSC analysis revealed the thermal stability of the formulations. The SEM analysis showed dense spherical particles. The toxicity study in albino rabbits showed no toxicity and was found biocompatible. The histopathological evaluation showed no signs of altered patterns. Results of this study highlighted a standard colonic drug delivery system with the ability to improve patient adherence and reduce GIT drug-associated side effects in CRC treatment.

Formulation and Evaluation of Tramadol HCL Pectin Coated Chitosan LDH Bionanocomposite Beads for Colon Drug Delivery System

Background: Tramadol HCl (TH) is a centrally acting analgesic that is used to treat mod-erate to severe pain intestinal disorders. Its use is limited orally due to instability. Objective: The study aims to develop TH Pectin-coated chitosan LDH bionanocomposite beads for colon targeting. Methods: LDH-TH intercalation was done by precipitation reaction and it was used to prepare bi-onanocomposite beads of TH. The developed beads were characterized for bulk density, tap density, angle of repose, HR, CI, particle size, SEM, swelling study, drug loading, and EE. In vitro release study in pH 1.2 HCl buffer, pH 6.8 buffer, and pH 7.4 buffer was performed. The compatibility study was performed using FTIR and DSC studies. Results: The optimised formulation (F8) was found to be spherical and smooth. All other micromerit-ics properties were found within the acceptable range with the particle size of 543μm to 888 μm. The amount of swelling is greatly influenced by the pectin concentration employed in the coating process. Drug loading of batches F1 to F8 ranged from 52.37% to 90.25%. % EE of batches F1 to F8 ranged from 71.92% to 88.78. FTIR and DSC studies showed no physical incompatibility between the drug and used excipients. Batch (F8) showed a more controlled release pattern at the highest coating con-centration of pectin (1.5%). The stability study also revealed that there was no change in the drug release profile. Conclusion: The developed beads can be used to target the colon to prolonged-release characteristics.

Starch hydrogels as targeted colonic drug delivery vehicles

Targeted colonic drug delivery systems are needed for the treatment of endemic colorectal pathologies, such as Crohn's disease, ulcerative colitis, and colorectal cancer. These drug delivery vehicles are difficult to formulate, as they need to remain structurally intact whilst navigating a wide range of physiological conditions across the upper gastrointestinal tract. In this work we show how starch hydrogel bulk structural and molecular level parameters influence their properties as drug delivery platforms. The in vitro protocols mimic in vivo conditions, accounting for physiological concentrations of gastrointestinal hydrolytic enzymes and salts. The structural changes starch gels undergo along the entire length of the human gastrointestinal tract have been quantified, and related to the materials' drug release kinetics for three different drug molecules, and interactions with the large intestinal microbiota. It has been demonstrated how one can modify their choice of starch in order to fine tune its corresponding hydrogel's pharmacokinetic profile.